484 Key to the System of 



2045. Panicle spikelike-contracted ... 2046 



Panicle spreading-branched ... ... ... ... 2048 



2046. Spikelets beset with silk-like vestiture. 



Leaves mostly glabrous ; panicle consisting of but few elon- 

 gated scattered and very slender branches, or occasionally 

 reduced to one or two spikes ; lowest bract very minute ; 

 the second bract three-streaked ; the third bract five- 

 streaked ; fruit-supporting bract smooth. 



F. leucophaeum. 



Spikelets almost or quite glabrous ... ... ... 2047 



2047. Spikelets very small, in unilaterally flowering distant 



Leaves from broad- to narrow-linear, involute along the 

 margin, glabrous ; spikes short, rather distant along the 

 undivided upper end of the stem, sometimes reduced to 

 mere clusters, their rhachis often setular-pointed ; spike- 

 lets usually close together in two rows, almost ovate- 

 ellipsoid, pale ; lowest bract ovate, about half as long as 

 the others ; second and third bracts five-streaked and 

 empty ; fruit-supporting bract wrinkled. P. gracile. 



Spikelets relatively large, almost racemously arranged. 



Never tall, somewhat prostrate ; leaves rather short, flat, 

 broadish ; branches of the inflorescence very short, pro- 

 duced from below the spikelets into an awn-like rough 

 elongation ; lowest bract minute, blunt ; second and 

 third bracts gradually much pointed, streaked by several 

 venules ; fruit obovate-ellipsoid. P. paradoxum. 



2048. Branches of the inflorescence awnlike-spinescent. 



Semiaquatic, much elongated and spreading ; stems and 

 branches compressed ; leaves broad, flat, their stalks lax ; 

 branches of the panicle spreading, very thin, scattered, 

 mostly undivided ; spikelets appressed but short-stalked, 

 scattered, comparatively long and proportionately narrow, 

 much pointed ; lowest bract minute, blunt ; second and 

 third bracts many-streaked ; stamens also within the 

 third bract ; fruit-supporting bract remaining tenderly 

 membranous, thus allowing of a ready secession of the 

 fruit. P. spinescens. 



Branches of the inflorescence without any awn-like 

 elongations ... ... ... ... .. ... 2049 



